Problem: Simplify the following expression: $n = \dfrac{x}{10} + \dfrac{x}{5}$
Answer: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $10$ and $5$ $\lcm(10, 5) = 10$ $ n = \dfrac{1}{1} \cdot \dfrac{x}{10} + \dfrac{2}{2} \cdot \dfrac{x}{5} $ $n = \dfrac{x}{10} + \dfrac{2x}{10}$ $n = \dfrac{x +2x}{10}$ $n = \dfrac{3x}{10}$